public class Main {
    public static void main(String[] args) {

    }
    public static void rotate(int[] a,int k){ //轮转数组
        k%=a.length;
        reverse(a,0,a.length-1);
        reverse(a,0,k-1);
        reverse(a,k,a.length-1);
    }
    public static void reverse(int[] a,int left,int end){
        while (left<end){
            int s=a[left];
            a[left]=a[end];
            a[end]=s;
            left++;
            end--;
        }
    }
    public static int fb(int n){ //斐波那契数列
        if (n==0){
            return 0;
        }
        if (n==1){
            return 1;
        }
        return fb(n-1)+fb(n-2);
    }
}